Impression techniques for multiple implants: a photoelastic analysis. Part I: comparison of three direct methods

The purpose of this article was to compare through photoelastic analysis the stress distribution in 3 direct transfer techniques for implants with splinting. Three photoelastic resin blocks were made with 2 implants placed parallel to each other and 2 square transfer copings splinted. Both transfers were splinted with acrylic resin chemically activated in 3 different techniques: metallic sticks (T1), prefabricated acrylic bars (T2), or dental floss (T3). A circular polariscope was used, and the distortion energy (E) was calculated in 4 periods: 20 minutes and 3, 24, and 36 hours. Statistically significant differences were found among the 3 techniques (P < .05). The dental floss presented the greatest distortion energy values (T3 = 0.469 Kgf/mm(2)) and the metallic sticks the lowest values (T1 = 0.0 Kgf/mm(2)). Thus, the metallic sticks technique (T1) appears to be the most accurate protocol to be used for implant-supported prosthesis with multiple abutments.